Liquid-ring gas pumps



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Oct. 29, 1963 R. LUHMANN 3,108,738

LIQUID-RING GAS PUMPS Filed Dec. 21, 1959 2' l "Ai 1?.- ,l ,0' 8f 4 /0 2{NVENTOR mmv/mw LuHMA/vn L Jia- ATTORNEYS United States PatentG3,108,738 LIQUlD-lllNG GAS PUMPS.

Reinhold Luhmann, itzehoe, Holstein', Germany, assignor to Siemen 8cHinsch m.b.H., Itzehoe, Holstein, Germany, a corporation oi? GermanyFiled Dec. 21, 1959, Ser. No. 861,062 Claims priority, applicationGermany Dee. 30, 1958 6 Claims. (Cl. 230-79) The present inventionconcerns liquid-ring gas pumps.

Known liquid ring gas pumps suffer from the disadvantages that theycause severe rattling noises when running with a high vacuum on thesuction side and a kind of humming noise when running at low vacuum onthe suction side. It is possible however, to achieve silent running inthe high vacuum range by the introduction of by-passed air on thesuction side, between the stages or in the impeller segments of thepumps. However, in some cases both the air delivery of these pumps inthe high vacuum range, and the maximum vacuum achievable areconsiderably reduced when by-passed air is used.

It has been found that there is a further possibility of eliminating thenoises in the high vacuum range by keeping the pressure chamber of thepump to a large extent free from liquid and by preventing the pressureslot from being covered with liquid. It was also found with low vacuumon the low suction side a cushion of liquid is desirable before thepressure slot, as this has a damping effect at the slot in thisoperating range on the outlet noises of the mixture of liquid and gas.

The object of the present invention is therefore to ensure silentrunning of the pump in the high vacuum range without any fall in outputin this working range. On the other hand, it indicates a possibility ofavoiding the humming noises which occur in the low vacuum range.

These advantages can be achieved, according to the invention, by liquidand gas being taken from the pressure chamber of the pump separately,with the connection for removal of the liquid arranged below thepressure slot. By means of an opening in the lower part of the pressurecasing of the pump, the working liquid may be allowed to ilow out, or itcan be drawn ofi from the pressure chamber with the aid of a specialliquid pump. The liquid and gas can then be conveyed into a jointcirculation container, or, alternatively, the liquid only may be takento this container and the gas forced out direct, provided adequateseparation of liquid and gas in the pressure chamber is assured; ifnecessary, however, this can be achieved by a suitable arrangement ofbaille vanes.

By means of a regulating valve in the pipe for removing the liquid,provision can be made to ensure that the separate removal of the liqiudfrom the pressure chamber of the pump is effected only under conditionsof high vacuum on the suction side of the pump, so as to make possiblethe formation of the desired cushion of liquid in the pressure chamberof the pump under conditions of low vacuum on .the suction side. It isparticularly advantageous if the regulating valve is controlled by thepressure of the pump on the suction side.

According to the design of the pump, it may suffice in the case ofmulti-stage pumps if only the last stage is so constructed that anaccumulation of liquid in the pressure chamber in front of the pressureslot is prevented, as it is often only the last stage which causes noisyworking.

A further advantage of the pump covered by the invention is thatobstruction in the liquid ring no longer occurs in the crown of the pumand overloading of the shaft or increased power consumption in the highvacuum range are prevented.

The invention will be described further, by way of ex- 3,1 018,738Patented Oct. 29, 1963 ice ample, with reference to the accompanyingdrawings in which:

FIG. 1 is a section through a single stage pump (on line B-B of FIG. 2).

FIG. 2. is a cross-sectional View :along line A-A of FIG. 1; and

FIG. 3 is a view similar to that of FIG. 1 of a twostage pump.

There is provided a casing 2 within which is eccentrically mounted animpeller 1. Gas enters the pump through a suction pipe 3 and a suctionslot 4 and is directed into the Vsegments formed by adjacent impellerblades and the liquid ring of the pump. The liquid required for theworking of the pump may be introduced at any point on the suction side16 of the pump or at the hub of the impeller. Due to the continuouslychanging volume of the segments during rotation of the impeller 1, amixture of liquid and gas is caused to leave the working chamber throughthe pressure slot 5 and to enter the pressure chamber 6 of the pump,which is separated from the suction chamber by a baille vane 7. Thegas-liquid mixture strikes the wall of the pressure chamber and possiblyalso separation vanes located therein, and the liquid and gas are thusseparated. The liquid collects in the lower part of the pressure chamber6, and can be drained off through a connected pipe 8. The gas leaves thepressure chamber of the pump through a connecting pipe 9. The liquidrequired for working of the pump, may, if there is an adequate naturalfall, ilow from the pressure chamber of the pump through the connectingpipe S under gravity. If there is no natural fall, liquid can be drainedoff by means of a special liquid pump 14 to which the connectionpipe 8is attached. In this way, the pressure slot S always remains free fromliquid.

Pump 14 drains liquid from the pressure chamber 6. Switching arrangement15, controlled by the pressure of pump 14, actuates magnetic valve 10.Vane 13 serves for the separation of liquid and gas in chamber 6. Liquidfrom pump 14 enters tank 17.

By means of a valve 10, it is possible to arrange that the liquidrequired for the operation of the pump flows out through the specialopening 8 only under conditions of high vacuum on the suction side ofthe pump. When conditions of low vacuum on the suction side of the pumpprevail the valve 10 is closed and liquid and gas leave the pumptogether through the connecting pipe 9.

FIG. 3 illustrates a two-stage pump designed in accordance with a secondembodiment of the invention. The reference numbers used are the same forboth stages but to prevent confusion an apostrophe is placed after thereference number in the case of the parts belonging to the second stage.The connections for directing the flow of gas and liquid from the iirstto the second stage are indicated by the reference numbers 11 and 12,the pipe 11 being for conveying the liquid and the pipe12 for conveyingthe gas. The valves 10 and 10' can of course, be used in the manner setout above when desired.

I claim:

1. A liquid ring gas pump having at least one stage in which at eachstage there is provided a casing, an eccentrically rotatable mountedvaned impeller within said casing, a suction chamber and a pressurechamber within said casing, gas and liquid inlets in said suctionchamber, gas and liquid outlets in said pressure chamber, means forintroducing gas and liquid into said suction chamber and for dischargingsaid gas and liquid through said gas and liquid outlets in said pressurechamber, said casing having a suction slot between said suction chamberand said impeller and a pressure slot between said impeller and saidpressure chamber, a valve in said liquid outlet, means responsive to thepressure in said suction chamber connected to said valve for openingsaid valve when the pump is Working at high vacuum in said suctionchamber to allow for the separate removal of gas and liquid from saidpressure chamber, said means closing said valve when the pump is Workingat low vacuum in said suction chamber to ensure the formation of acushion of liquid in said pressure chamber.

2. A liquid ring gas pump as set forth in claim 1 in which said liquidoutlet is located below said pressure slot.

3. A liquid ring gas pump as set forth in claim 1 in which there is abaille in said casing dividing said casing into said suction andpressure chambers.

4. A liquid ring gas pump as set forth in claim 1 in which said liquidand gas outlets are spaced apart a sufficient distance to allowseparation of said liquid from said gas.

5. A liquid ring gas pump as set forth in claim l in which a pluralityof stages are provided in parallel.

6. A liquid ring gas pump as set forth in claim 1 in which a separateliquid pump is provided at said liquid 5 outlet and said liquid is drawnoff `by said separate liquid pump from said pressure chamber.

References Cited in the tile of this patent UNITED STATES PATENTS

1. A LIQUID RING GAS PUMP HAVING AT LEAST ONE STAGE IN WHICH AT EACH STAGE THERE IS PROVIDED A CASING, AN ECCENTRALLY ROTATABLE MOUNTED VANED IMPELLER WITHIN SAID CASING, A SUCTION CHAMBER, AND A PRESSURE CHAMBER WITHIN SAID CASING, GAS AND LIQUID INLETS IN SAID SUCTION CHAMBER, GAS AND LIQUID OUTLETS IN SAID PRESSURE CHAMBER, MEANS FOR INTRODUCING GAS AND LIQUID INTO SAID SUCTION CHAMBER AND FOR DISCHARGING SAID GAS AND LIQUID THROUGH SAID GAS AND LIQUID OUTLETS IN SAID PRESSURE CHAMBER, SAID CASING HAVING A SUCTION SLOT BETWEEN SAID SUCTION CHAMBER AND SAID IMPELLER AND A PRESSURE SLOT BETWEEN SAID IMPELLER 